Hyperspectral imaging refers to the imaging of a scene over a large number of discrete, contiguous spectral bands such that a complete reflectance spectrum can be obtained for the region being imaged. The basic process of hyperspectral imaging is as follows. Firstly, the light source system gives out light of a certain waveband to irradiate on the surface of an object. Secondly, the light reflects, scatters, and transmits on the surface of the object and inside the object. Thirdly, one part of reflectance light enters the hyperspectral imaging camera beam splitting system and is caught by a sensor inside the camera. At last, hyperspectral images are output after being processed by signals such as photovoltaic conversion. In the hyperspectral imaging process, the light source system plays a very important role. It provides energy input for the whole imaging system. The arrangement of light source system determines the reflection path of the light on the surface of the object. With a steady light source system and a rational light arrangement, it could guarantee the hyperspectral imaging system obtain images with high quality and high stability.
At present, halogen lamps are used as light sources for hyperspectral imaging systems, and diffuse reflection is the main method to obtain the images. For example, in a patent application “A Device For Detecting Agricultural And Animal Products and Method thereof With Hyperspectral imaging Technology” with application number of 200610097857.5, halogen lamps and UV lamps are used as the light sources to obtain the reflected spectral images of the agricultural and animal products. In a patent application “A device For Detecting Fruits and method thereof With Hyperspectral imaging Technology” with application number of 200520099328.x, halogen lamps and laser lights are used as the light sources of the high spectrum image system, the light converges on the surface of the fruits after being transmitted by two optical fibers, and a converging lens is placed in front of the camera lens. Although above-mentioned two disclosed devices can meet the basic requirements for obtaining hyperspectral images, the disadvantages thereof comprise: 1. The light source system are not optimized, for example the luminous efficiency and light intensity will change with the increase of the service life of the halogen lamp, and the energy loss when the light transmits in the optical fibers and so on. 2. The method of the light source to irradiate the object is singular, the method that the light irradiates on the object directly by means of forming a certain angle with the carrier plane can hardly ensure uniform light.